1. Field of the Invention
The present invention relates to digital imaging, and more specifically, creating high-quality S-parameter images in real-time.
2. Background
Positrons are known for their sensitivity to vacancy type defects in solids. Using Doppler broadening spectroscopy, the shape of the 511 keV annihilation line, as represented through the S-parameter, provides a helpful measure of neutral and negatively charged vacancy defects. S-parameter imaging of a wafer surface by laterally scanning a point source of positrons across the wafer surface can provide useful information regarding the density of bulk defects in the wafer. Such scans have been made in the past by moving a radioactive source or a positron beam across a wafer. In this method, the beam or radioactive source is kept fixed and one point on the sample is exposed to that radiation for some fixed time and all annihilation events are then recorded for that point before moving on to the next point. The next point is then exposed to the positron radiation and so on until the whole sample surface has been scanned. The whole data set is finally processed off-line as per the requirement and is finally plotted in the form of an S-parameter graph using plotting software.